Dwarf galaxies found around the Milky Way

Two dim dwarf galaxies are the Milky Way?s newest-known galactic companions, astronomers studying a vast swath of sky reported on Monday. This brings the total number of dwarf galaxies in the Milky Way?s cosmic neighbourhood to 14.

Two dim dwarf galaxies are the Milky Way’s newest-known galactic companions, astronomers studying a vast swath of sky reported on Monday. This brings the total number of dwarf galaxies in the Milky Way’s cosmic neighbourhood to 14.

But theorists believe there could conceivably be hundreds more. The two newly detected dwarfs were found in the direction of the constellations Canes Venatici (the hunting dogs) and Bootes (the herdsman), scientists studying the Sloan Digital Sky Survey said in a statement.

The little galaxy found in Canes Venatici is about 640,000 light-years from the Sun, a stone’s throw in cosmic terms. A light-year is about 10 trillion kilometres, the distance light travels in a year.

The dwarf found in Bootes is about the same distance from the Sun. Even though they are close, these galaxies were hard to spot because they were so dim, a defining characteristic of dwarf galaxies.

The new galaxy in Bootes is the faintest discovered, with a total luminosity of 100,000 Suns. Some astronomers theorise that there should be hundreds of clumps of so-called cold dark matter — slow-moving subatomic particles left over from the earliest period of the universe — orbiting the Milky Way, which contains Earth. Each of these clumps should be massive enough to host a dwarf galaxy, but so far only 14 have been found.